Calculation Method for Elastic Modulus of Soil-Rock Mixture Based on Meso-Structure Model

The invention relates to the field of mesoscopic numerical technology of geotechnical materials, in particular to a calculation method for an elastic modulus of soil-rock mixture based on a mesoscopic structure model.

In practical engineering, the physical and mechanical properties of soil-rock mixture materials are not only mainly affected by the material composition and structure of geotechnical materials, but also mainly affected by the occurrence environment, especially the in-situ stress environment. It can be seen that the elastic modulus, as an important physical and mechanical parameter of the soil-rock mixture, is not only affected by the stone content, but also has the confining pressure effect caused by the in-situ stress.

Due to the complex fabric characteristics of the soil-rock mixture, it has a high degree of inhomogeneity, discontinuity, spatial variability, and environmental dependence. Due to the different contents of the internal components, and the differences in particle shape, spatial distribution, and arrangement, the macro and micro mechanical properties are very different. The traditional macroscopic analysis method cannot consider the internal meso-structure characteristics, and it is difficult to describe the meso-mechanics between different components and the influence of meso-structure on macro-mechanical properties. The development of the numerical simulation method based on the meso-structure model provides the possibility to study the meso-structural mechanical characteristics and macro-mechanical behavior of materials, and then put forward the relationship between meso-structural characteristics, external factors, and macro-physical and mechanical parameters. In the previous study of soil-rock mixture, the mechanical parameters of the soil-rock mixture are usually determined by only testing the soil matrix in the soil-rock mixture and multiplying by a certain correction coefficient. This method has great randomness and cannot consider and describe the influence of internal structure on the macroscopic mechanical properties of materials.

In order to solve the above problems, the invention proposes a calculation method for the elastic modulus of soil-rock mixture based on a mesoscopic structure model, which effectively solves the problem that it is difficult to present effective physical and mechanical parameters in engineering design and construction, and can be directly used in practical engineering composed of soil-rock mixture materials.

In order to achieve the above purpose, the invention discloses the following technical solution.

A calculation method for an elastic modulus of soil-rock mixture based on a mesoscopic structure model comprises the following steps:

Preferably, the construction of the two-dimensional random meso-structure model of the soil-rock mixture comprises the following: based on a grid mapping method, generating the two-dimensional random meso-structure model of the soil-rock mixture with different stone contents according to an original gradation.

Preferably, a calculation formula of the equivalent elastic modulus of the soil-rock mixture is as follows:

wherein E denotes the macroscopic equivalent elastic modulus of the soil-rock mixture, σ-σdenotes deviatoric stress, and ε represents the axial strain.

Preferably, an acquisition of the macroscopic equivalent elastic modulus of the soil-rock mixture considering the stone content and confining pressure comprises the following steps:

where E denotes the macroscopic equivalent elastic modulus of the soil-rock mixture, ζ denotes the stone content, σdenotes a confining pressure, and E, a, b, c, d, and e are parameter coefficients of the regression model respectively.

The beneficial effects of the invention are as follows:

According to the screening test, the particle gradation curve of the soil-rock mixture is obtained, and the random meso-structure model of the soil-rock mixture is generated according to the gradation curve, the generated model has geometric similarity with the undisturbed soil-rock mixture, which ensures the credibility of the numerical test results based on this model. This method solves the problem that it is difficult to present effective physical and mechanical parameters in the geological materials of soil-rock mixtures, the randomness of the previous physical and mechanical parameter selection methods is also solved, and the influence of internal structure on the macroscopic mechanical properties of materials is considered and solved.

In order to make the purpose, technical solution, and advantages of the invention more clear, the invention is further described in detail in combination with the attached drawings and an embodiment, it should be understood that the specific embodiment described here is only used to explain the invention and are not used to limit the invention.

A calculation method for the elastic modulus of the soil-rock mixture based on the mesoscopic structure model is shown in, which comprises the following steps:

Specifically, the placement area of the soil-rock mixture is subdivided to establish a grid model;

Specifically,shows the particle gradation curve of the soil-rock mixture obtained by screening test of a fault-filling soil-rock mixture, according to the original gradation, a two-dimensional random meso-structure model of soil-rock mixture with different stone contents is constructed, where the soil-rock mixture sample is set to be a rectangle with a diameter of 200 mm and a height of 400 mm, the grid unit size of the grid model is 2 mm, and the stone contents are 10%, 15%, 20%, 30%, 50%, and 70%, respectively, the two-dimensional random meso-structure model of soil-rock mixture with different stone contents is shown in.

Secondly, the finite element method is used to carry out the biaxial compression numerical tests under the condition of 10%, 15%, 20%, 30%, 50%, and 70% stone contents, and the confining pressures are 200 kPa, 400 kPa, 600 kPa, 800 kPa and 10 MPa respectively.

Then, through the corresponding secant elastic modulus when the axial strain is equal to 1%, the macroscopic equivalent elastic modulus E of soil-rock mixture under the conditions of stone content of 10%, 15%, 20%, 30%, 50%, and 70% and confining pressure of 200 kPa, 400 kPa, 600 kPa, 800 kPa, and 10 MPa is determined. the formula is as follows:

Finally, the binary quadratic polynomial regression model is used to express the relationship between the macroscopic equivalent elastic modulus of the soil-rock mixture and the stone content and confining pressure:

where E denotes the macroscopic equivalent elastic modulus of the soil-rock mixture, ζ denotes the stone content (unit %), σdenotes a confining pressure (unit kPa), and E, a, b, c, d, and e are parameter coefficients of the regression model respectively. According to the calculated macroscopic equivalent elastic modulus E of the soil-rock mixture, the regression model of macroscopic equivalent elastic modulus E of the soil-rock mixture considering stone content and confining pressure is obtained as follows:

The above content is only the better embodiment of the invention and is not used to limit the invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the invention should be comprised in the protection scope of the invention.